JPS591940B2 - Air conditioner refrigeration circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration cycle for an air conditioner,
One of the objectives is to enable multi-purpose refrigeration cycle control with one bypass pipe.

Conventionally, in the refrigeration cycle of an air conditioner, a bypass pipe is installed between high and low pressure pipes, and a solenoid valve is installed in this bypass pipe. It is possible to stop and circulate the refrigerant flow in one direction, but it is not possible to stop the refrigerant flow in the opposite direction, or it is possible to stop and circulate the refrigerant flow in one direction, but the refrigerant flow in the opposite direction is not possible. Since this was possible, it was only possible to stop and allow the refrigerant flow to flow in one direction in the bypass pipe.

That is, a conventional solenoid valve used in a bypass circuit of this type of refrigeration cycle was constructed as shown in FIG.

In FIG. 3, a solenoid valve 10b, an inlet pipe a, an outlet pipe b1
It is composed of a valve body 12 whose position is fixed, a plunger 13 that is pulled up by an electromagnetic coil 14, a cylindrical body 11 that houses a spring 15 that pushes down this plunger 13, etc., and performs the following operations.

Assuming that the electromagnetic coil 14 is now in a non-energized state, the cylinder body 1
1 and the plunger 13, the pressure Pa inside the inlet pipe a and the cylinder body 11 and the plunger 1
The pressure Pc in the space created by the surface in contact with the spring 15 of No. 3 is equal.

Then, the area of the surface where the plunger 13 contacts the spring 15 is Ap, the cross-sectional area of the hole 17 in the valve body 12 is AV, the force of the spring 15 to push down the plunger 13 is Fsl, and the weight of the plunger is FP. Press down force F of jar 13, F1=Fs+FP+AP-
It becomes Pa.

On the other hand, the force F that tries to push the plunger 13 upward
2B becomes F2-AV/PR.

Generally, the relationship between the areas AP and AV is A p > A y, so at least when the pressure Pa > Pb, the forces F1 and F
2, since Fl>F2, Pushinger 13 is pushed downward with a strong force'! The hole 16 of the valve body 12 is closed by the tip of the plunger 13, and the inlet pipe a and the outlet pipe A do not communicate with each other.

When the electromagnetic coil 14 is energized from this state, the coil 14
Since the plunger 13 is pulled up by the force Fc due to the magnetic force of
connects the inlet pipe a and the outlet pipe A.

On the other hand, when the coil 14 is de-energized, if the pressure pb in the outlet pipe becomes somewhat thicker than the pressure Pa in the inlet pipe a, F2>
A state Fl occurs, and the plunger 13 is pushed upward, and since the coil 14 is de-energized and the outlet pipe is closed, the flow to the inlet pipe a cannot be stopped.

Therefore, the flow of refrigerant in the bypass pipe changes in the direction of flow between cooling and heating operations, and the flow of refrigerant in the bypass pipe stops, and the refrigerant cannot flow freely. If a solenoid valve is installed so that the refrigerant flow can only be stopped and allowed to flow from the high-pressure pipe to the low-pressure pipe, the flow of refrigerant in the bypass pipe can only be stopped and allowed to flow during cooling operation, but not during heating operation. This has the disadvantage that it becomes impossible to stop the flow of refrigerant flowing in the opposite direction through the bypass pipe, or it becomes impossible to flow the refrigerant through the bypass pipe at all.

In other words, during cooling operation, when there is an overload or low load condition, by flowing refrigerant in a timely manner through this bypass pipe, the overload or low load condition can be eliminated, and during heating operation, the heat source side It is possible to create a bypass circuit to remove frost from the heat exchanger, or to perform a bypass to balance high and low pressure when the compressor is stopped, but on the other hand, refrigerant always flows through the solenoid valve during heating operation. However, since the refrigerant does not flow through the solenoid valve, overload control, low load control, and pressure equilibrium promotion when the compressor is stopped are not possible. .

The present invention eliminates the drawbacks found in the conventional refrigeration cycles described above.

Hereinafter, the present invention will be described with reference to the accompanying drawings showing one embodiment thereof.

In FIG. 1, the refrigeration circuit is constructed by sequentially connecting a compressor 1, a four-way valve 2, a heat source side heat exchanger 3, a throttle device 4, and a user side heat exchanger 5. A first pipe line 6 connecting the expansion device 4, a user-side heat exchanger 5, and a four-way valve 2
A bypass pipe 8 is connected to the second conduit 7 that connects the 2nd conduit 7, and a bypass pipe 8 is provided in which the valve can be closed even if the differential pressure across the valve is small in both directions when not energized, and in both directions when energized. Bidirectional solenoid valve 9 allowing flow and having an inlet pipe a and an outlet pipe a
has been established.

Next, with reference to FIG. 2, the above-mentioned bidirectional solenoid valve will be explained.

This two-way solenoid valve 9 includes an inlet pipe a1, an outlet pipe, and a valve body 20 whose positions are fixed, a plunger valve 23 that is pulled up by an electromagnetic coil 21 and has a valve hole 22 at its tip 26, and this plunger It is composed of a cylindrical body 25 that houses a spring 24 and the like that push down the jar valve 23.

Here, the operation of the bidirectional solenoid valve 9 will be explained.

Assuming that the coil 21 is in a non-energized state and the pressure Pa inside the inlet pipe a is higher than the pressure Pb inside the outlet pipe,
The tapered tip 26 of the Pushinger valve 23 is pressed in the direction Pd by a force from the inlet pipe a side to the outlet pipe side.

As a result, the left side of the tip 26 of the plunger valve 23 and the valve body 20 are firmly pressed together, and there is no leakage from the inlet pipe a to the outlet pipe.
Since there is a slight gap on the right side of the cylinder body 25, the pressure pc in the space between the cylinder body 25, the plunger valve 23, and the valve body 20 becomes the same as the pressure Pa.

Therefore, in the non-energized state, the inlet pipe a and the outlet pipe A do not communicate with each other, and when the electromagnetic coil 21 is energized from this state, the pulling force F1 of the plunger valve 23 of the electromagnetic coil 21 is
In other words, it is only necessary to have the attraction force F1 of the coil that is greater than the sum of the force Fs of the spring 24 and the self-weight FP of the plunger valve 23, so that it can be immediately pulled up.

This is exactly the same even when the pressure Pb inside the outlet pipe is greater than the pressure pa inside the inlet pipe a, Pb>Pa, and the difference between the pressure Pa inside the inlet pipe a and the pressure pb inside the outlet pipe is Even if there is a large difference, that is, Pa≧pb
However, even if Pa≦pb, the valve can be opened and closed.

In the above configuration, the refrigerant discharged from the compressor 1 during cooling operation passes through the four-way valve 2, the heat source side heat exchanger 3, the first pipe line 6, the expansion device 4, the user side heat exchanger 5, the second pipe line 7, and the four-way Assume that the flow passes through valve 2 in sequence and returns to compressor 1 again.

Also, at this time, since the bidirectional solenoid valve 9 in the bypass pipe 8 de-energizes the coil 21 as described above,
The inlet pipe a and the outlet pipe A do not communicate with each other.

Therefore, no refrigerant flows through the bypass pipe 8.

Here, the pressure Pa in the first pipe line 6 has abnormally increased due to the temperature and humidity conditions of the heat source side heat exchanger 3 and the user side heat exchanger 5, so in order to lower the pressure Pa, the bidirectionality in the bypass pipe 8 is When the solenoid valve 9 is opened, the operation of the two-way solenoid valve 9 is performed as described above, and the refrigerant flows through the bypass pipe 8 from the first pipe side to the second pipe line 7 side, reducing the pressure Pa. and compressor 1
can prevent overload operation.

In addition, during this cooling operation state, the pressure PB in the second pipe line 7 may drop abnormally, and the liquid refrigerant may return to the compressor 1, or the heat exchanger 5 on the user side may become frosted, resulting in a so-called low load state. Similarly, the coil 21 of the two-way solenoid valve 9 is energized, the refrigerant is caused to flow from the first pipe line 6 to the second pipe line 7, and the pressure pb is increased.
Low load conditions can be avoided.

Furthermore, when the compressor 1 is stopped during this cooling operation, the coil 21 of the bidirectional solenoid valve 9 is energized to flow the refrigerant from the first pipe line 6 in a high pressure state to the second pipe line 7 in a low pressure state.
As a result, the pressure difference between the pressure pa in the first pipe line 6 and the pressure pb in the second pipe line 7 is reduced in a short time, and the compressor 1
You can also make it easier to restart.

On the other hand, during heating operation, the refrigerant discharged from the compressor 1 flows through the four-way valve 2, the second pipe line 7, the user-side heat exchanger 5, the expansion device 4, and the first
It is assumed that the flow passes through the pipe line 6, the heat source side heat exchanger 3, and the four-way valve 2, and returns to the compressor 1 again.

Also, at this time, the bidirectional solenoid valve 9 in the bypass pipe 8 de-energizes the coil 21 as explained earlier, so when the outlet pipe is connected, the inlet pipe a is not communicated, and the refrigerant does not flow through the bypass pipe 8. .

Here, as in the case of cooling earlier, the pressure in the second pipe line 7 is pb depending on the temperature and humidity conditions of the heat source side heat exchanger 3 and the user side heat exchanger 5.
When the pressure rises abnormally, a so-called overload condition, the two-way solenoid valve 9 in the bypass pipe 8 is opened to reduce the pressure pb.

Therefore, the operation of the two-way solenoid valve 9 is performed by energizing as described above, and the refrigerant flows through the bypass pipe 8 from the second pipe line 1 side to the first pipe line 6 side, reducing the pressure pb, and the compressor 1. Prevent overload operation.

Also, in this heating operation state, when the pressure Pa in the first pipe line 6 abnormally decreases and the liquid refrigerant returns to the compressor 1, which is a so-called low load state, the bidirectional solenoid valve 9 By energizing the coil 21, the refrigerant can flow from the second pipe line 7 to the first pipe line 6, increasing the pressure Pa and avoiding a low load state.

Furthermore, when the compressor 1 is stopped during heating operation, the coil 21 of the bidirectional solenoid valve 9 is energized to flow the refrigerant from the second pipe line 7 in a high pressure state to the first pipe line 6 in a low pressure state.
It is also possible to reduce the pressure difference between the pressure pb in the second pipe line 7 and the pressure Pa in the first pipe line 6 in a short time, thereby making it easier to restart the compressor 1.

Furthermore, in order to remove frost on the heat source side heat exchanger 3 during heating operation, the coil 21 of the bidirectional solenoid valve 9 in the bypass pipe 8 is energized when the cooling cycle is temporarily switched. It is also possible to defrost the heat source side heat exchanger 3 by flowing the refrigerant through the bypass pipe 8, leaking the amount of heat absorbed by the use side heat exchanger 5, and preventing cold air from coming out from the use side heat exchanger 5.

By the way, if the conventional solenoid valve 10 shown in FIG. 3 is used instead of the two-way solenoid valve 9, the operation will be the same as the previous one during cooling operation, but the second pipe 7 side will be closed during heating operation. pressure pb
Since the pressure Pa becomes higher than the pressure Pa on the first pipe line 6 side, the plunger 13 is pushed up, and therefore, if the outlet pipe is constantly closed, the inlet pipe a will be connected, and the heating capacity will be reduced.

As a result, using the conventional solenoid valve 10, the bidirectional solenoid valve 9
cannot be replaced.

However, if it is necessary to use the solenoid valve 10, it is necessary to use two outlet pipes facing each other, which is expensive and prone to failure.

As described above, the refrigeration circuit of the air conditioner according to the present invention is provided so that one bypass pipe can serve as the high pressure side and low pressure side during cooling operation and the high pressure side and low pressure side during heating operation. Inside is a bidirectional solenoid that can open and close the valve even if there is a large pressure difference in both directions when not energized.One solenoid valve can handle overloads and low loads during cooling and heating operations.
low temperature) control, promoting pressure balance when the compressor is stopped, and bypass control during defrosting operation.
Furthermore, the circuit has many advantages, such as being able to simplify and inexpensively manufacture the circuit, and making maintenance extremely easy.

[Brief explanation of drawings]

Fig. 1 is a refrigeration circuit diagram of an air conditioner according to an embodiment of the present invention, Fig. 2 is a sectional view of a bidirectional solenoid valve that constitutes the refrigeration circuit, and Fig. 3 is a refrigeration circuit diagram of an air conditioner according to an embodiment of the present invention. It is a sectional view of a solenoid valve. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Four-way valve, 3... Heat source side heat exchanger, 4... Throttle device, 5... User side heat exchanger, 6
...First pipe line, 7... Second pipe line, 8... Bypass pipe, 9... Bidirectional solenoid valve.

Claims (1)

[Claims] 1 Cooling operation in the first pipe line that forms a refrigerant circulation circuit with a compressor, a four-way valve, a heat source side heat exchanger, a throttling device, and a user side heat exchanger, and connects the heat source side heat exchanger and the user side heat exchanger. A bypass pipe is used to connect a pipe line section that becomes high pressure during heating operation and low pressure during heating operation to a second pipe line connecting the user-side heat exchanger and the four-way valve. A refrigeration circuit for an air conditioner equipped with a bidirectional solenoid valve that can close the valve even if the differential pressure across the valve is small and allows flow in both directions when energized.